Method of assembling a scroll compressor

Abstract

A scroll compressor includes an electric motor formed of a stator and a rotor, the rotor having a shaft which is supported by upper and lower bearings. To ensure precise alignment of the upper bearing, lower bearing, and stator within the tubular shell, the lower bearing is a two-piece assembly comprising an outer ring portion and an inner bearing plate. The upper bearing, the stator, and lower bearing outer fing portion are inserted into the tubular shell. An alignment arbor, in the form of a spindle carrying the lower bearing outer ring portion, is inserted into the stator. The upper bearing is installed in the shell onto the arbor. The alignment arbor is expanded against the stator, the upper bearing and the lower bearing outer ring portion to ensure precise alignment. Then the upper bearing, crankcase and lower bearing outer ring portion are affixed, e.g. welded to the tubular shell. The arbor is collapsed and withdrawn. Then the rotor is inserted, and the inner bearing plate of the lower bearing is installed to journal the lower end of the rotor shaft. This compressor assembly significantly simplifies the assembly process while achieving precise alignment. This yields improved reliability, startability, and efficiency.

What is claimed is: 
     
       1. A method of assembly of a scroll compressor of the type in which a tubular shell contains an armature stator which has a cylindrical passage therethrough of a predetermined radius, a rotor assembly has a shaft which is rotatably journalled above and below the stator in an upper bearing and a lower bearing, respectively, which are fixedly disposed within said tubular shell, and a cylindrical rotor is affixed concentrically on said shaft fitting within the passage of said stator, compressor means mounted above said upper bearing and driven by said rotor shaft for compressing a gas, and upper and lower end cap means which close off upper and lower ends of said tubular shell; the method comprising the steps of: installing and securing said stator within said shell;   installing an outer ring portion of said lower bearing into said shell below said stator, said outer ring portion having a central opening therein that has at least as large a radius as that of the passage of said stator, by placing the outer ring portion onto an alignment arbor and inserting same into the shell, so that the alignment arbor passes through said stator;   placing said upper bearing onto the alignment arbor above said stator;   expanding said alignment arbor radially to lock said upper bearing, said stator, and said lower bearing outer ring portion in predetermined precisely aligned positions within said shell;   affixing said precisely aligned upper bearing and lower bearing outer ring portion onto the interior wall of said shell;   withdrawing said alignment arbor;   installing said rotor assembly through said opening in the lower bearing outer ring portion so that the upper end of the shaft is journalled in said upper bearing and said rotor is positioned within the cylindrical passage of said stator;   installing a central bearing plate member onto said lower bearing outer ring portion to journal the lower end of said shaft in precise alignment with respect to said upper bearing and said stator; and   installing said compressor means and said upper and lower end cap means.   
     
     
       2. The compressor assembly method of claim 1 wherein said affixing the upper bearing and the lower bearing outer ring portion to said tubular shell includes welding radially outer portions of a crankcase that carries said upper bearing and radially outer portions of said lower bearing outer ring to said tubular shell. 
     
     
       3. The compressor assembly method of claim 1 wherein said lower bearing outer ring portion has a plurality of bores therethrough radially beyond said central opening, and said bearing plate member has a like plurality of bores therethrough in registry with the first mentioned bores, and said steps of installing said bearing plate member onto said lower bearing outer ring portion includes aligning the bores of the plate member with the bores of the outer ring portion and securing them together with threaded fasteners passing through the aligned bores. 
     
     
       4. The compressor assembly method of claim 1 wherein said alignment arbor is generally in the form of a spindle having an upper expandable, generally cylindrical portion to align said upper bearing, a central expandable, generally cylindrical portion to position against said stator, and a lower expandable generally cylindrical portion to align the lower bearing outer ring portion. 
     
     
       5. The compressor assembly method of claim 4 wherein said alignment arbor further includes a radial flange at a lower edge of said lower expandable portion.